Suction accumulator

ABSTRACT

The suction accumulator of the invention is designed for use with the suction or compression side of a refrigeration system. The accumulator comprises a casing having an inlet and an outlet. An outlet tube structure is provided within the casing connected to an outlet from the casing. The outlet tube structure includes an outer tube and an inner tube of smaller diameter positioned therewithin. This structure extends from a point adjacent the bottom of the casing to the casing outlet and acts as a suction device to draw liquid from the casing and expel it into the casing outlet at a metered rate.

United States Patent Rockwell et a1.

[ Sept. 24, 1974 1 SUCTION ACCUMULATOR Primary Examine'rMeyer Perlin [75] Inventors: Frank H. Rockwell; Edward W. g i Agent or Flrm*whlttemore Hulbert &

Bottum, both of Brighton, Mich. e nap [73] Assignee: Refrigeration Research, Inc.,

Brighton, Mich. [57] ABSTRACT The suction accumulator of the invention is designed [22] Flled 1973 for use with the suction or compression side of a re- [21] Appl. No.: 411,913 frigeration system. The accumulator comprises a casing having an inlet and an outlet. An outlet tube structure is provided within the casing connected to an out- C(11. let from the casing. The Outlet tube Structure includes [58] d 62/468 503 an outer tube and an inner tube of smaller diameter le 0 positioned therewithin. This structure extends from a point adjacent the bottom of the casing to the casing [56] References Clted outlet and acts as a suction device to draw liquid from UNITED STATES PATENTS the casing and expel it into the casing outlet at a me- 3,012,414 12/1961 La Porte 62/503 tered rate. 3,111,819 11/1963 Williams 62/503 4 Claims, 4 Drawing Figures I 36 I I l K I I Ix /5 I I 42 l a I I1- .I.L -gI R;

I I -36 I II I I II m I l I :1 I I |I 1 40 I 1 I II I I I I I i I II //0 l 1 I II I II //2 I :I I I I II I I I I I] I I I //4 I I H I I I I I Z6 I I I I I I I I I I i "22 I I I I I I *I :1 111i A? BACKGROUND OF THE INVENTION The suction accumulator to which the present invention pertains is particularly adapted for use in refrigeration systems such as air conditioning, heat pump, truck refrigeration and many other applications which require intermittent operation of the refrigeration compressor. The suction accumulator is provided between the evaporator and compressor of a refrigeration system. Vaporized refrigerant is received from the evaporator and passed on through the suction accumulator to the compressor.

During the off cycle of such systems, large quantities of liquid often return through the suction line and find their way into the compressor crankcase when a suction accumulator is not provided. This is especially true in remote applications where the suction line may trap or hold quantities of liquid which may suddenly be dumped into the compressor as the compressor starts up. This is frequently the cause of broken valves, pistons, broken or bent connecting rods, blown gaskets and bearing washout.

When a suction accumulator is used, liquids such as refrigerant and lubricating oil are collected in the accumulator and slowly metered to the compressor. The metering protects the compressor against undue shock resulting from large amounts of liquid being present in the compressor crankshaft being suddenly injected into the compressor from the suction line. The metering also prevents liquid refrigerant from forcing the oil out of the bearings causing bearing washout. Bearing washout results in the bearings and compressor motor burning out.

A number of patents have issued in the past directed to suction accumulators, for example, US. Pat. Nos.: 3,084,523, 3,212,289, 3,344,506, 3,420,071, 3,444,367, 3,563,053, 3,589,395, 3,609,990, 3,626,715, 3,643,465, 3,643,466, 3,012,414. Such prior constructions generally employ a U-tube which acts as a conduit for refrigerant gas to pass through the accumulator and on to the compressor. The U-tube is provided with a small metering opening which extends to the bottom of the accumulator casing. This opening acts as a metering opening to slowly draw liquid from the easing into the U-tube to thereby meter the amount of liquid which passes from the accumulator to the compressor. Other systems have been suggested wherein a single tube of small diameter is used as a metering device.

The present invention provides an improved version wherein a straight inner tube is provided within a straight outer tube. The outer tube is open at the top for the ingress of gaseous refrigerant thereinto. A small opening is provided in the bottom of the outer tube for metering of liquid thereinto. The gaseous refrigerant passes into the outer tube down to the bottom thereof and then up the inner tube which is connected to the compressor. Thus, essentially, a single elongated tubular device is provided within the accumulator casing.

The single tubular structure provides more space within the accumulator casing which permits use of other structure within the casing such, for example, as a heat exchange coil and also permits a single casing to be used with a wider range of tube sizes which is especially important in connection with the large tube size.

SUMMARY OF THE INVENTION A suction accumulator for a refrigeration system is provided. The accumulator includes a casing having a inlet and an outlet. An outlet tube structure is provided within that casing. This structure comprises an outer tube and an inner tube of smaller diameter positioned therewithin. The inner tube extends from the outlet towards the lower portion of the casing. The lower end of the inner tube is open. The outer tube has a closed lower end and extends over the inner tube towards the upper portion of the casing and terminates in an open end for the passage of gas through the outer tube and thence through the inner tube. The outer tube has an opening adjacent to the lower portion of the casing to draw liquid from the casing and expel it into the casing outlet at a metered rate.

IN THE DRAWINGS FIG. 1 is a side elevational view in section along line ll of FIG. 2 of one embodiment of the suction accumulator of the present invention;

FIG. 2 is a top plan view of the suction accumulator of FIG. 1;

FIG. 3 is a bottom view of an enlarged scale of the tubular structure provided within the casing of the suction accumulator of F IG. 1; and

FIG. 4 is a sectional view of the lower portion of the tubular structure taken substantially along the line 4--4 of FIG. 3.

DESCRIPTION OF A PREFERRED EMBODIMENT As illutrated in the Figures, the suction accumulator 10 includes a casing 12 which comprises an openended tube 14 having an upper end closure 16 and a lower end closure 18 secured thereto as by brazing. While the accumulator 10 is shown with the longitudinal axis vertically oriented, this axis may also be oriented horizontally with the inlets and outlets approximately re-arranged. Further, the inlets and outlets may enter the sides as well as through the top as shown in FIG. 1.

An outlet fitting 20 extends through the upper end closure 16 into the interior of the casing 12. An elongated inner tube 22 is attached at one end to the fitting 20. The tube 22 extends downwardly to a point adjacent the lower end closure 18. The lower end 24 of the tube 22 is open and is cut along a bias.

The inner tube 22 is received within an outer tube 26. The tube 22, 26 may be fabricated of, for example, steel. The diameter of the inner tube 22 is significantly less than the diameter of the outer tube 26. For example, in one embodiment, the inner tube 22 has a diameter of 1 V4 inches, while the outer tube 26 has a diameter of 2 inches. Thus there is considerable unoccupied space within the outer tube 26 permitting flow of gaseous material therethrough. The inner tube 22 is secured to and positioned against the inner surface of a wall portion of the outer tube 26 as by welding. The bias along which the lower end of the inner tube 22 is defined extends from the contacted wall surface of the outer tube 26 upwardly towards the oppositely disposed wall portion of the outer tube to increase the effective size of the opening into the inner tube 22.

A cap 28 is provided on the lower end of the outer tube 26. A recess 30 is formed centrally of the cap 28. A small metering opening 32, for example, an opening one-eighth inch in diameter, is formed centrally'of the recess 30. A screen 34 is spot welded over the recess 30 to act as a strainer for fluid passing through the opening 32 into the outer tube 26. The screen 34 may be, for example, 30 X 50 mesh and fabricated of monel metal. Another small opening 36 is provided adjacent the upper end of the inner tube 22 to equalize pressure within the tubes 22, 26.

An inlet tube 38 also extends through the upper end closure 16. The inlet tube 38 extends for a short distance into the casing. One wall portion 40 of the tube 38 is deformed inwardly into the tube 38 to form a scoop for directing the flow of incoming fluid into the casing.

In operation of the accumulator, cold refrigerant gas having a small amount of entrained liquid refrigerant therein enters the accumulator through the inlet tube 38. The incoming gases, which move at a relatively high velocity, are directed tangentially against the inner wall of the casing and generally follow a circular path around the casing interior. The gases are then free to expand, with resultant reduction of the velocity thereof. As a consequence, incoming gases are not directed as a high-speed jet against any liquid which may be retained in the lower portion of the casing. This prevents turbulence of the liquid which may result in objectionable foaming and also prevents splashing of liqaid.

The refrigerant gases which enter the casing are drawn into the upper open end 42 of the outer tube 26. Thesegases pass downwardly through the outer tube 26 and thence into the open lower end 24 of the inner tube 22. The gases are passed from the innter tube 22 through the outlet fitting 20 and thence to the compressor of the refrigeration system (not shown). The compressor, which creates a suction, draws the gaseous refrigerant through the accumulator at a relatively rapid rate.

Liquid refrigerant which enters the accumulator through the inlet tube 38 drops to the bottom of the accumulator and is subsequently drawn through the opening 32 and then through the inner tube 22 and out of the accumulator. It will be appreciated that the liquid which is metered into the inner tube 22 is entrained in the stream of gaseous refrigerant. It remains entrained in the gas as it passes from the accumulator and is drawn to the compressor of the system. The opening 32 acts as a restriction and causes liquid refrigerant to be metered into the compressor at a controlled rate. The accumulator thus acts to prevent large amounts of liquid refrigerant from suddenly entering the compressor. Such sudden surges ofliquid may result in seriously damaging the compressor.

During operation of the refrigeration system, there are times when an unusual amount of refrigerant will collect in the accumulator. For example, -when the system is shut off, such as in the case with an intermittently operated air conditioning system, the refrigerant tends to condense in the entire systemand collect in the accumulator. A similar situation may occur when the system is operated under low load conditions. The metering of the liquid refrigerant through the opening 32 results in liquid refrigerant being delivered to the compressor at a non-harmful rate.

What we claim as our invention is:

l. A suction accumulator for a refrigeration system comprising a casing, an inlet to the casing, an outlet from the casing, an outlet tube structure comprising an outer tube and an inner tube of smaller diameter positioned therewithin, said inner tube extending from the outlet towards the lower portion of the casing, the lower end of the inner tube being open, the outer tube having a closed lower end and extending over the'inner tube towards the upper portion of the casing and terminating in an open end for the passage of gas through the outer tube and thence through the inner tube and out of the outlet from the casing, said outer tube having an opening therein adjacent the lower portion of the casing to draw liquid from the casing and expel it into the casing outlet at a metered rate.

2. A suction accumulator as defined in claim 1, further characterized in that the lower open end of the inner tube is formed along a bias with respect to the longitudinal axis of the inner tube to thereby present a larger area for communication with the outer tube for free passage of gas from the outer tube through the inner tube.

3. A suction accumulator as defined in claim 2, further characterized in that the inner tube is positioned against the inner surface of a wall portion of the outer tube to thereby define a passageway in the outer tube around the inner tube, the bias along which the lower end of the inner tube is defined extending from the contacted wall surface of the outer tube upwardly towards the oppositely disposed wall portion of the outer tube.

4. A suction accumulator as defined in claim 1, further characterized in the formation of a recess in the lower end of the outer tube, said opening in the outer tube being formed in said recess, and a screen secured over the recess externally of the outer tube to strain foreign particles from liquid flowing-into the outer tube through said opening. 

1. A suction accumulator for a refrigeration system comprising a casing, an inlet to the casing, an outlet from the casing, an outlet tube structure comprising an outer tube and an inner tube of smaller diameter positioned therewithin, said inner tube extending from the outlet towards the lower portion of the casing, the lower end of the inner tube being open, the outer tube having a closed lower end and extending over the inner tube towards the upper portion of the casing and terminating in an open end for the passage of gas through the outer tube and thence through the inner tube and out of the outlet from the casing, said outer tube having an opening therein adjacent the lower portion of the casing to draw liquid from the casing and expel it into the casing outlet at a metered rate.
 2. A suction accumulator as defined in claim 1, further characterized in that the lower open end of the inner tube is formed along a bias with respect to the longitudinal axis of the inner tube to thereby present a larger area for communication with the outer tube for free passage of gas from the outer tube through the inner tube.
 3. A suction aCcumulator as defined in claim 2, further characterized in that the inner tube is positioned against the inner surface of a wall portion of the outer tube to thereby define a passageway in the outer tube around the inner tube, the bias along which the lower end of the inner tube is defined extending from the contacted wall surface of the outer tube upwardly towards the oppositely disposed wall portion of the outer tube.
 4. A suction accumulator as defined in claim 1, further characterized in the formation of a recess in the lower end of the outer tube, said opening in the outer tube being formed in said recess, and a screen secured over the recess externally of the outer tube to strain foreign particles from liquid flowing into the outer tube through said opening. 